1. Field of the Invention
This invention relates to control strategies for thermally activated diverter valves when used in a washing appliance. In particular, this invention relates to methods of switching a thermally actuated valve during operation of a recirculation cycle in a laundry washing appliance.
2. Summary of the Prior Art
Currently, many washing appliances use as a means of introducing or diverting water to the water receptacle of the appliance a thermally activated valve which is turned on when electricity is supplied to its electrical contacts, thereby heating the wax within the actuator and operating the switching of the valve from a first position (closed) to a second position (open). Usually, during the recirculation phase of a wash cycle the valve diverts water from the water receptacle and through a pipe to be recirculated back into the water receptacle. At the start of a wash cycle, the water receptacle is filled and the valve is energised. After some delay due to thermal actuation the valve is fully opened and allows water to be recirculated through the bowl. When the valve is closed and a pump turned on, the water within the receptacle is pumped through the valve to the drain.
Usually, once the thermally activated valve is switched on it takes a minute or so before it is fully activated and in an open position. Once activated and after the washing appliance""s water receptacle has been filled, by way of an inlet valve, to a predetermined level, the recirculation phase of the wash cycle starts and water is pumped from the receptacle through the valve and directed back into the receptacle. The time taken for the receptacle to fill with water to the predetermined level usually corresponds to the time taken for the valve to warm up and be activated. Therefore, the valve is activated at approximately the same time as the washing appliance is ready to start the recirculation phase of the wash cycle.
In areas where there is a low water pressure and therefore a low flow rate the time generally taken for the bowl to fill with water to the predetermined level required for the recirculation phase may be as long as, for example, 10 minutes. Therefore in low water pressure areas, the valve is activated and is open after approximately one minute and is running hot. As valves of this type have a finite xe2x80x98on timexe2x80x99 life then the life of the valve is being shortened, as during a long fill cycle the valve is unnecessarily on.
There may be other situations that also result in a low flow rate of water into the appliance. Some examples are when valves or pipes are blocked. Therefore in all situations where the flow rate is low the valves life is being shortened.
It is therefore an object of the present invention to provide a control strategy for a thermally activated diverter valve when used with a washing appliance which will go at least some way to overcoming the abovementioned disadvantages or will at least provide the industry with a useful choice.
Accordingly, in a first aspect the invention consists in a washing appliance which has a recirculating wash cycle comprising or including:
(a) a water holding receptacle,
(b) an inlet valve that admits water to fill said water holding receptacle to a predetermined level,
(c) a pump, which pumps water from the receptacle,
(d) a thermally actuated diverter valve connected to the outlet of said pump, which when energised opens to divert water from the pump back into the receptacle and when not actuated allows water to be discharged from the receptacle, and
(e) control means, which energises said diverter valve at or near the time taken for water in said receptacle to reach said predetermined level.
In a second aspect the invention consists in a method of controlling a thermally actuated diverter valve during a recirculation cycle of a washing appliance, wherein said washing appliance comprises or includes a water holding receptacle, an inlet valve, a pump connected to said diverter valve, and control means which stores a program which causes the control means to:
(a) open said inlet valve and fill said receptacle with water to a predetermined level,
(b) close said inlet valve,
(c) energise said thermally activated diverter valve at or near the time taken to reach said predetermined level,
(d) activate said pump, which pumps water from the receptacle through said diverter valve and back into said receptacle, and
(e) de-energise said diverter valve at the end of said recirculation cycle to allow for water to be discharged from said receptacle.
In a third aspect the invention consists in a method of controlling a thermally activated diverter valve during the recirculation cycle of a washing appliance, wherein said washing appliance comprises or includes a water holding receptacle, an inlet valve, a pump, and control means which stores a program and monitors a low flow rate flag, said program causing said control means to control a first wash phase and subsequent wash phases, said method including the steps of:
(a) said control means monitoring said low flow rate flag, and either commencing said washing cycle by switching on said inlet valve and filling said receptacle to a predetermined water level if said flag is set, or
energising on said diverter valve and opening said at least one inlet valve, then commencing said washing cycle if said flag is not set,
(b) said control means monitoring said water level within said receptacle, and either
clearing said flag if said predetermined water level has been reached and the time taken to fill said receptacle to said predetermined water level is less than a minimum time, then switching on said diverter valve if said diverter valve is not already on and commencing said first wash phase, or
leaving said flag unchanged if said predetermined water level has been reached and said time taken to fill said receptacle to said predetermined water level is greater than said minimum time, then energising said diverter valve if said diverter valve is not already energised and commencing the recirculation wash phase, or
leaving said flag unchanged if said predetermined water level has not been reached and said time taken to fill said receptacle to said level has taken less than a maximum time then continuing with step b), or
setting said flag if said predetermined water level has not been reached and said time taken to fill said receptacle is greater than said maximum time and said flag is not already set, then de-energising said diverter valve and continuing with step b), or
leaving said flag if said predetermined water level has not been reached and said time taken to fill said receptacle is greater than said maximum time and said flag is already set, then continuing with step b) until said receptacle is filled with water to said predetermined water level,
(c) starting the first wash phase of said wash cycle and de-energising said diverter valve during said first wash cycle, and
(d) continuing with said subsequent wash phases until said wash cycle is completed.
In a fourth aspect the invention consists in a method of controlling a thermally activated diverter valve during the cycle of a washing appliance, wherein said washing appliance comprises or includes a water holding receptacle, an inlet valve, a pump, and control means which stores a program and causes the control means to:
open said inlet valve and energise said diverter valve and fill said receptacle with water to a predetermined water level,
monitor the time taken to fill said receptacle to said predetermined water level, and commence said wash cycle,
complete said wash cycle,
wherein in a subsequent wash cycle before commencement of said subsequent wash cycle the energising of said diverter valve is delayed to said monitored time taken to fill said receptacle less a thermal activation time, and
said subsequent wash cycle is commenced once said predetermined water level is reached.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.